How to Seal a Leak Under the Sink

Cleveland Van CecilUpdated February 21, 2017

A kitchen sink has only a few parts that can break, but when they do, major leaks can occur. The sink drain is connected to a strainer assembly. The strainer assembly meets with the "P" or "U" trap under the sink. This is where bits of food or grease collect so that they don't go down the drain leading away from the house. Leaks are most common between the strainer assembly and the trap assembly.

Loosen the coupling nut on the underside of the sink drain using a pair of slip-joint pliers.

Slide the handles of a 16-inch slip nut plier into the drain basket of the sink.

Position a screwdriver between the handles and turn the wrench counterclockwise using the screwdriver to give you extra leverage. Unscrew the drain until it comes out of the sink.

Roll a small piece of plumber's putty between your hand to make a snake shape. Connect the putty so it is a circle and place it around the drain hole. Screw the drain basket down onto the putty to seal. Remove any extra putty that squeezes out.

Place a bucket underneath the trap.

Loosen the nuts holding the trap in place with slip-joint pliers. Drain the water in the trap into the bucket.

Remove the pipe leading from the sink strainer to the trap. Check the washer and replace if broken. Replace the pipe if it is cracked. Also inspect the washers of the trap.